Meta Description - Not Specified: Google automatically set the Meta description as per the search query according to the content in the page.If Meta Description Specified: It must be unique as possible/(search engine/user)/friendly descriptive comment as Meta description.

Meta Description and Meta keywords are not a mandatory fields (If the page content speaks).

Ideally yes. It is better to have a meta description and meta keyword for all your main pages because when Google visits your site and happens to see no meta tags it will simply copy paste the content of your page onto description and when it shows up in search results it may be broken into parts and incomplete sentence. Hence, the user will get an exact idea as to what the site is about.
I would recommend using it.

Pages & Tools

Services

Let's Forum is an internet discussion community that helps folks (webmasters) involved in online marketing, search engine optimization and website development or design. Learn with us the necessary stuff that will boost your website to the top. Check out our how to make money site where we discuss on ways to earn money online on the Internet and or work from home. Fast | Easy | Free.